Bovine Ac-globulin is to be isolated by methods developed in this laboratory. The purified protein is to be studied with the view of learning about its structure, and how it is digested by purified thrombin. If the hypothetical peptide(s) obtained with thrombin can be isolated, an attempt is to be made to start on amino acid sequencing. In the case of chicken thrombin, prothrombin, prothrombin fragment 1, and prothrombin fragment 2, an attempt is to be made at getting the fragments in purified form and obtain enough amino acid sequence information to compare with comparable bovine and human material. Indications are that homology is extensive, and that the avian molecule has much resemblance to that of the mammalian.